The objective of this proposal is to determine whether clinically inapparent human placental infection with Coxiella burneti, the agent of Q Fever, leads to fetal infection, and, if so, whether such infection results in birth defects detectable in the newborn or developing child. Silent, clinically inapparent infections of man and domestic animals with C. burneti are numerous and widespread in many parts of the world, including Maryland. Inapparent recrudescence of infection occurs in pregnancy without any obvious deleterious effect on the newborn. Using C. burneti agglutination reaction that measures specific IgM antibodies, we propose to screen cord sera obtained, at time of delivery, from hospitals in Maryland situated in areas of concentrated dairying. Quantitative IgM determinations will be carried out on the cord sera positive for C. burneti agglutinins, elevated IgM being indicative of fetal infections. Isolation of C. burneti from the cord blood clots and from the placentas corresponding to the positive cord sera will be attempted. The children born with proven C. burneti infection will be followed clinically for the detection of possible defects that might be imputable to intrauterine infection with C. burneti.